[hurd, commited] hurd: _hurd_intr_rpc_mach_msg() might not preserve the correct reply port

[Samuel Thibault]

From: Mike Kelly <mike@weatherwax.co.uk>

Calls to mach_msg_trap() that return MACH_SEND_INTERRUPTED modify the message header. A subsequent attempt at sending the message can return EINTR for handling by the caller. Mig generated code (expecting the message header to be unaltered) now fails assertion in __mig_dealloc_reply_port(). Fixed by restoring the altered message header content before reattempting RPC message delivery.
Message-ID: <20260209204213.91782-2-mike@weatherwax.co.uk>
---
 hurd/intr-msg.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hurd/intr-msg.c b/hurd/intr-msg.c
index 02e514400f..83db9413ab 100644
--- a/hurd/intr-msg.c
+++ b/hurd/intr-msg.c
@@ -136,6 +136,13 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
 	}
       if (!(option & MACH_SEND_INTERRUPT))
 	{
+	  m->header.msgh_local_port = rcv_name;
+	  m->header.msgh_remote_port = remote_port;
+	  m->header.msgh_id = msgid;
+	  m->header.msgh_bits = msgh_bits;
+	  /* Restore the two words clobbered by the reply data.  */
+	  m->request.data = save_data;
+
 	  option = user_option;
 	  timeout = user_timeout;
 	  goto message;
-- 
2.51.0